1. Field of the Invention
The present invention relates to a water pump for a vehicle. More particularly, the present invention relates to a water pump for a vehicle of which performance thereof is improved and leakage of coolant is prevented.
2. Description of Related Art
Generally, a cooling apparatus of a vehicle maintains the temperature of an engine in operation to be constant. In addition, the cooling apparatus is a water-cooled type using coolant or an air-cooled type using exterior air.
The air-cooled type uses a method in which the engine directly contacts the air. The air-cooled type does not need a coolant supplied thereto, thus leakage and freezing of coolant do not occur, and the system is simple. However, uniform cooling of the engine according to an operation condition thereof is difficult and a large amount of noise occurs in the air-cooled type, so this type is not widely used.
The water-cooled type uses coolant for cooling the engine, and is separated into a gravity circulation type and a forced circulation type according to the circulating type of the coolant. The coolant is circulated by convection in the gravity circulation type, and thus the gravity circulation type is not appropriate for a high performance engine.
Meanwhile, the forced circulation type is the typical circulation type currently used for vehicles, and the coolant is circulated by an operation of a water pump in the forced circulation type. In addition, the forced circulation type is most appropriate for high performance engines. That is, the water pump is provided for circulating the coolant in the engine using the water-cooled type.
In addition, the water pump is operated by always being in direct contact with the coolant. Meanwhile, a failure of a bearing may be generated or the lifetime of a belt may be reduced when the coolant leaks from the water pump. Therefore, a sealing member is mounted at a drive shaft of the water pump so as to prevent leakage of coolant. In addition, a drain hole is formed at the water pump housing for preventing coolant in a gaseous state and including particles from passing the sealing member and permeating to the bearing.
However, aesthetic features may be deteriorated if the coolant is exhausted to the outside through the drain hole. In addition, the manufacturing cost of the water pump is increased if a sealing member having a high cost is used for improving sealing performance. Further, cavitation occurs such that noise and vibration is generated since rotation speed of an impeller is not constantly maintained in a conventional water pump. Furthermore, components of the impeller can be damaged by the cavitation.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.